The present invention relates to a cable-position monitoring device for monitoring the position of a cable, which is guided in the rollers of a roller assembly, in at least one first cable roller that is to be monitored in the roller assembly of a cable operated transportation system comprising the at least one first and at least one second cable roller defining a reference roller.
Furthermore, the present invention relates to a cable operated transportation system incorporating a cable, a drive device for moving the cable and at least one roller assembly for guiding the cable, wherein the at least one roller assembly comprises at least one first cable roller and at least one second cable roller defining a reference roller, wherein furthermore, there is provided a cable position monitoring device for monitoring at least the position of the cable guided in the at least one first cable roller.
Moreover, the present invention relates to a method for monitoring the position of a cable, which is guided in the rollers of a roller assembly, in at least one first cable roller that is to be monitored in a roller assembly of a cable operated transportation system comprising the at least one first and at least one second cable roller defining a reference roller.
In cable operated transportation systems, aerial cableways in the form of chair lifts or gondola cars for example, the carrier-, traction- and/or hoisting cables of the transportation system are guided over cable rollers. As a rule, the cable rollers are arranged on supports in the landscape, whereby a plurality of cable rollers together can form a roller assembly. The cable rollers of the transportation system serve either as supporting rollers upon which the cable rests, or as hold-down rollers which hold the cable down, i.e. the cable is guided under the cable rollers. In none of these cases however is the cable guided over its full extent. As a consequence thereof, the cable can jump off the cable rollers in certain conditions, due to the transverse forces arising as a result of wind or jolting movements for example. In such a case, the cable is moved parallel to an axis of rotation of the cable roller and can escape from a guide slot in the cable roller.
For the purposes of safeguarding the transportation system, so-called cable grabbers are usually arranged on the supports carrying the cable rollers which catch the cable after it is dislodged from one or more of the rollers. Operation of the transportation system is interrupted conventionally by the release of a break-bar switch which is actuated by the dislodged cable. Thus, the position of the cable can only be detected in two positions in the manner described. Either the cable is being guided in the cable roller or the cable rollers, or it is already dislodged. Clear guidance as to whether there is or is not a threat of the danger of a cable becoming dislodged cannot be established in the manner described.
A circuit arrangement for monitoring the fault free state and/or for detecting a faulty state, in particular for monitoring the position of the cable in an aerial cableway or chair lift system, is disclosed in DE 197 52 362 A1. In this disclosure, it is proposed in particular that the position of the cable be monitored by means of inductive or capacitive proximity switches. This, however, has the disadvantage that it is necessary for the proximity switches to be installed in a very precise manner in order to enable reliable information in regard to the state of the system to be given. Furthermore, the use of proximity switches has the disadvantage that the positioning of the proximity switches has to be altered as the period of operation of the transportation system increases due to wear of the cable rollers.
Consequently, it would be desirable to improve a cable position monitoring device, a cable operated transportation system and a method of monitoring the cable position of a cable operated transportation system of the type described hereinabove in such a way that a threatening cable-dislodgement of the cable from at least one cable roller of the transportation system can be recognized in a simple manner.